On Thu, May 25, 2023 at 05:28:08PM -0700, Darrick J. Wong wrote: > Hi all, > > As part of merging the parent pointers patchset into my development > branch, I noticed a few problems with the GETFSMAP implementation for > XFS. The biggest problem is that ranged queries don't work properly if > the query interval is exactly within a single record. It turns out that > I didn't implement the record filtering quite right -- for the first > call into the btree code, we want to find any rmap that overlaps with > the range specified, but for subsequent calls, we only want rmaps that > come after the low key of the query. This can be fixed by tweaking the > filtering logic and pushing the key handling into the individual backend > implementations. > > The second problem I noticed is that there are integer overflows in the > rtbitmap and external log handlers. This is the result of a poor > decision on my part to use the incore rmap records for storing the query > ranges; this only works for the rmap code, which is smart enough to > iterate AGs. This breaks down spectacularly if someone tries to query > high block offsets in either the rt volume or the log device. I fixed > that by introducing a second filtering implementation based entirely on > daddrs. > > The third problem was minor by comparison -- the rt volume cannot ever > use rtblocks beyond the end of the last rtextent, so it makes no sense > for GETFSMAP to try to query those areas. > > Having done that, add a few more patches to clean up some messes. > > If you're going to start using this mess, you probably ought to just > pull from my git trees, which are linked below. > > This is an extraordinary way to destroy everything. Enjoy! > Comments and questions are, as always, welcome. > > --D > > kernel git tree: > https://git.kernel.org/cgit/linux/kernel/git/djwong/xfs-linux.git/log/?h=getfsmap-fixes > > xfsprogs git tree: > https://git.kernel.org/cgit/linux/kernel/git/djwong/xfsprogs-dev.git/log/?h=getfsmap-fixes > --- > fs/xfs/libxfs/xfs_alloc.c | 10 -- > fs/xfs/libxfs/xfs_refcount.c | 13 +- > fs/xfs/libxfs/xfs_rmap.c | 10 -- > fs/xfs/xfs_fsmap.c | 261 ++++++++++++++++++++++-------------------- > fs/xfs/xfs_trace.h | 25 ++++ > 5 files changed, 177 insertions(+), 142 deletions(-) Changes look sensible, but I know my limits: I'm not going to find off-by-one problems in this code during review. Reviewed-by: Dave Chinner <dchinner@xxxxxxxxxx> -- Dave Chinner david@xxxxxxxxxxxxx
